Companion plants I

The concept of companion plants is found especially in small gardens and in organic gardens and rely on the idea that the plants can benefit one from the company of others. A whole interconnected system works and have the purpose to assure the efficient growth and development of plants and to replace the chemical insecticides and herbicides with organic prevention and pest control – attracting beneficial insects, birds and other animals.

The advantages of using this system are:

Nitrogen fixation.

Some plants like beans and pea, with the help of bacteria that live on their roots, have the capacity to fix nitrogen in soil. So the need of using this fertilizer is reduced or lacks.

Secretion of insecticides or pest repelling substances.

The tagetes for example, secrete from different parts of them (roots, leaves, flowers), substances which kill nematodes, substances which have insecticide and fungicide effects or substances with unpleasant smell for some insects.

Secretion of substances which don’t inhibit the germination, growth and development of other plants.

The walnut inhibits the growth of many plants around him. Also the rye straw secretes a substance which inhibits the growth of some weeds (Epilobium hirstum, Conyza canadensis). The fennel inhibits almost any neighbouring plant except for dill. Knowing this you can protect some plants by not growing them together or you can use them as organic herbicides.

Using some plants as traps for pests and drawing these pests away from the main crops.

Some pest insects are attracted especially to certain plants. The black aphids for example, are attracted to nasturtium. Growing this plant near a tomato, the aphids will prefer the nasturtium. So you can protect this way the tomato.

Attraction of predatory insects which feed themselves with pest insects.

The ladybugs feed themselves with aphids and are attracted usually to plants with umbel flowers (dill, carrots) or to dandelions, cosmos, calendulas, tagetes etc. Parasitic insects (some wasps) which lay their eggs inside the body of other insects (pest insects), can be attracted to mint, parsley, tagetes, zinnia, lavender etc.

Reduction or absence of competition for food resources between plants.

The bean and pea grown together compete for the same substances from soil. Some plants have longer roots as others and look for food at deeper levels than the last ones.

Shadow shelter or wind protection from tall and bushy plants to small ones.

For example, jasmine tobacco can provide some sun shelter to the lettuce.

Providing climbing support from tall plants to the climbing ones.

The bean can climb on corn stalk.

Reducing the risk of losing the entire crop by having a diversity of plants.

The pest insects or some disease can destroy a whole plot migrating very fast from a plant to its neighbor. This can be stopped by growing different plants near each other. The pests have their preferences.

Reducing the risk of being attacked by pests camouflaging some plants with others.

For example, the anise can hide the smell of cabbage, cauliflower or other Brassicaceae plants. The smell of tagetes can confuse the pests which look somewhere else for their favorite food.